1. Field of the Invention
The present invention relates to a machining method for forming micro-concave portions (oil reservoirs) used to achieve a reduction in friction in an inner circumferential surface of a cylindrical bore (round hole) such as in a cylinder block of a vehicle engine.
2. Background Information
Several machining methods for forming micro-concave portions in inner circumferential surfaces of cylinders in cylinder blocks have been proposed. On proposed method includes forming grooves having a specified depth in a lattice pattern by laser machining the inner circumferential surface of the cylinder that has been machined beforehand. Then, notches that are shallower than the grooves are similarly formed by laser machining in the surfaces surrounded by these grooves. These grooves and notches function as lubricating oil holding parts (oil reservoirs). One example of this type of machining method for forming micro-concave portions is disclosed in Japanese Laid-Open Patent Application No. 7-40068
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved machining method. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.